1. Field of the Invention
The present invention relates to a wiring substrate having a built-in component (hereinafter referred to as a “component-incorporated wiring substrate”) in which a plate-like component is incorporated.
2. Description of Related Art
A known package is configured as follows: build-up layers are formed on respective opposite sides of a core substrate so as to configure a wiring substrate, and an IC chip or a like device is mounted on the wiring substrate. In recent years, in association with an increase in speed and the number of terminals of IC chips, supply of power to the IC chip mounted on the wiring substrate from an external board involves a problem of malfunction caused by unstable supply voltage or noise. In order to cope with the problem, the wiring substrate incorporates a component, such as a capacitor, for stabilization of supply voltage or elimination of noise. For example, Patent Document 1 discloses a wiring substrate having a structure in which electronic circuit components are accommodated in respective holes of a base substrate, and terminals of the electronic circuit components are soldered to electrode pads of a wiring layer. By use of such a technique, there can be implemented, for example, a wiring substrate having a structure in which a chip capacitor is employed as a built-in electronic circuit component and connected to a supply voltage line. In the case of using the above-mentioned wiring substrate having build-up layers formed on respective opposite sides of the core substrate, after the chip capacitor is accommodated in an accommodation hole formed in the core substrate, via conductors are formed at predetermined positions in insulation layers, which are formed on the respective opposite sides of the core substrate and partially constitute the build-up layers, for electrically connecting the surfaces of terminal electrodes of the chip capacitor to upper and lower conductor layers.